Electrodeposition of nickel and electrolytes therefor



United States Patent 3,376,207 ELECTRODEPOSITION OF NICKEL AND ELECTROLYTES THEREFOR Harry Axel Herman Ericson, Warby, Fittja, Sweden, as-

fsiignor to Patent-Serm A-G., Lucerne, Switzerland, a

rm N0 Drawing. Filed May 17, 1965, Ser. No. 456,541 26 Claims. (Cl. 204-49) The present invention relates to the electrodeposition of nickel from an aqueous acidic nickel plating bath and, more particularly, to the production of bright and level elcctrodeposits of good ductility and adherence.

It is known to modify nickel electroplating baths with brightening agents as well as with agents to improve leveling effects. However, it has been observed that during the electroplating process when the bath contains conventional brightening and leveling agents, hydrogen is evolved at the cathode in quantities sufiicient to produce deleterious effects which result in reduced corrosion protection for the base metal.

It is, therefore, an object of this invention to provide an electroplating process whereby bright, level and adherent nickel electrodeposits can be obtained free from the disadvantageous effects of hydrogen evolution at the cathode which substantially reduces the corrosion protection desired for the base metal.

Another object of this invention is to provide an additive for nickel plating baths from which bright, level, ductile and adherent nickel deposits may be obtained.

A further object of this invention is to provide an additive for nickel plating baths which is employed to reduce the evolution of hydrogen at the cathode so as to produce on the base metal a porous-free deposit having increased corrosion protection characteristics.

With the foregoing objects in view, as well as others which will become apparent as the description proceeds, the invention consists in the novel plating process, the novel additive and bath compositions which will be described in certain illustrative examples hereinafter and which will then be more particularly pointed out in the appended claims.

It has now proved possible to produce nickel coatings with high brightness and good ductility by employing nickel plating baths containing a brightener selected from the group of compounds having the following structural formula:

wherein R, R R and R are selected from the group consisting of hydrogen, alkanyl, alkenyl, alkynyl, the hydroxy derivatives of said alkanyl, alkenyl and alkynyl radicals, amino and sulfonic acid groups, and X is halogen. Preferably, the alkanyl, alkenyl and alkynyl radicals have 1-6 carbon atoms.

Representative sulfolanylethers having the structural formula CH2CHOR include methyl sulfolanylether, ethyl sulfolanylether, hydroxyethylene sulfolanylether, butyl sulfolanylether, propyl sulfolanylether, hydroxybutylene sulfolanylether, vinyl sulfolanylether, l-propenyl sulfolanylether, 2-proinclude methylamino sulfolane, 2-propenylamino sulfolane, propargylamino sulfolane, N -propargylamin0, N -ethyleneamino sulfolane, sodium sulfolanyl taurate, dihydroxydiethyleneamino sulfolane, N-hydroxyethylene N-2-propenylamino sulfolane, N-hydroxyethylene-N-propargylamino sulfolane, N-butyl, N-propargylamino sulfolane, N -propargylamino, N -butyl-N -ethyleneamino sulfolane, sodium sulfolanylmethyl taurate, dipropenylamino sulfolane, N-propenyl-N-propargylamino sulfolane, sodium sulfolanylpropenyl taurate, dipropargylamino sulfolane, N -propargylamino, N -propargyl-N -ethyleneamino sulfolane, sodium sulfolanylpropargyl taurate, di-N -propargylamino, N -ethyleneamino sulfolane, sodium sulfolanyl, N -propargylamino, N -ethyleneamino taurate, disodium sulfolanylpropargyl taurate, tetraamino tetraethylene aminosulfolane, propargylamino-triamino-tetraethylene aminosulfolane, propargylamino-diamino-triethylene aminosulfolane, and propargylamino-monoamino-diethylene aminosulfolane.

Representative preferred sulfolanylesters having the structural formula include acetyl sulfolanylester chloride, acryl sulfolanylester chloride. It has also been found 3-su1folanol can also be advantageously employed as well as 3-sulfolene which has the power to act as a source of sulfur dioxide. 3-sulfolene decomposes in sulfur dioxide and butadiene. At 70 C. the decomposition rate is approximately 0.1% per hour. In situations where hexavalent chromium is present or where execptionally good throwing or covering power is desired sulfolene is an excellent addition agent to the aqueous acidic nickel plating bath.

The novel brighteners of this invention are generally used in amounts between 0.01 and 10 millimoles per liter of bath solution and preferably between 0.02 to 1.0 millimole per liter of solution.

In general, the process of the invention involves operating a bath at conventional nickel plating temperatures ranging from about 30 C. to as high as C. with a range of 4065 C. being especially desirable. The pH of the plating bath, as determined electrochemically, can range from around 1.5 to 5.0 with 3.0 to 5.0 being found especially suitable in the majority of cases. Practically all baths for electroplating nickel contain nickel sulfate, 2 chloride, usually nickel chloride, a buffering agent, usually boric acid and a wetting agent. Such types of baths include the well-known Watts-type bath and high chloride type bath. The Watts bath solution to which the novel brightener of this invention can be added typically comprises around 300 grams per liter of nickel sulfate, 60 grams per liter of nickel chloride and 40 grams per liter of boric acid. The foregoing bath composition and specified operating conditions are not critical in the basic Watts bath solution and the particular temperature and pH thereof may vary Within the indicated ranges Without adverse effects. Considerable latitude is also permissible in respect to the types and concentrations of the nickel salts employed, for instance, as the source of nickel, a combination of nickel fluoborate with nickel sulfate and nickel chloride, or a combination of nickel fluoborate with nickel chloride can be used.

In another embodiment of this invention the nickel plating bath solution can contain, in addition to the novel brightener of this invention, a brightener of the first class which is, preferably, an aromatic sulfur compound such as p-toluene sulfonamide, o-benzoyl sulfimide, benzene sulfonarnide, naphthalene tri-sulfonic acid, benzene sulphonic acid, Z-butyne, 1,4-disulphonic acid, allyl sulphonic acid together with Z-butyne, 1,4-dioxyethanesulphonic acid or sodium saccharate. Generally the aromatic sulfur compound will be present in amounts ranging from 0.1 to 30 grams per liter of solution. Additionally, if the bath is air agitated, comparable brightening effects are obtained with a substantially less brightener concentration. In this latter instance the novel brightener of the invention is generally employed in amounts ranging between 0.025 to 2.5 millimoles per liter of solution while the brightener of the first class advantageously is employed in amounts ranging from 0.05 to 15 grams per liter of solution. A mirror bright deposit of high luster is obtained when using this combination of brighteners especially when the novel brightener of this invention is an unsaturated aminosulfolane.

Various wetting agents can be used in association with the novel plating bath compositions of this invention such as sodium lauryl sulfate, sodium lauryl ether sulfate and 7-ethyl-2-methyl-4 undecanol. Further, wetting agents which can be used have the following formula and are used in amounts of 0.5 to 5 grams per liter:

wherein R is an alkanoyl group having 8 to 10 carbon atoms, R is selected from the group consisting of hydrogen, aliphatic, alicyclic and aromatic radicals, R is an aliphatic bridge containing from 1 to 5 carbon atoms and R is selected from the group consisting of hydrogen and alkali metals. Representative wetting agents of this type are sodium octanoyl taurate, potassium nonanoyl methyl taurate, sodium decanoyl methyl taurate, sodium octanoyl cyclohexyl taurate, sodium nonanoyl methyl phenyl taurate, sodium decanoyl phenyl taurate, sodium octanoyl cyclopropyl taurate, octanoyl hexyl amino propylene sultonic acid, sodium salt of decanoyl cyclobutyl amino butylene sulfonic acid, and octanoyl tauric acid.

To reduce the sensitivity of the novel nickel plating bath compositions of this invention with respect to metallic and/ or organic contaminants, a hydroxy derivative of an aromatic sulfur compound such as sodium tetrahydroxynaphthalene sulfonic acid can be added to the bath solution as a sequestering agent. Preferably, the sequestering agent is employed in amounts of 0.1 to 5 grams per liter of plating solution.

For the purpose of giving those skilled in the art a better understanding of the invention, illustrative examples are given. In the examples, an aqueous acidic nickel-containing bath was made up with the specified components. Electrodeposition was carried out by passing electric current through an electric circuit comprising an anode and 'a sheet metal or rod cathode, both immersed in the bath. The bath-s were agitated, usually by a moving cathode although in certain instances air agitation was employed. The examples utilizing the novel brighteners of this invention resulted in a nickel coating with improved leveling effects and corrosion resistance properties. In the examples employing, additionally, a brightener of the first class, i.e. an aromatic sulfur compound, the resulting sulfur-containing nickel coating also exhibited mirror bright characteristics as well as stress-free properties.

In the examples, the following standard Watts-type bath was used as a base solution:

Nickel sulfate g./l

' 300 Nickel chloride g./l 60 Boric acid g./l 40 pH 3.0-5.0 Temperature C 40-60 EXAMPLE 1 Propargyl sultolanylether mmol/l 0.3 Sodium saacharate g./l 1.5 Sodium lau-ryl sulfate g./l 0.1 Current density 'amperes/dm. 1-10 EXAMPLE 2 Hydroxybutynyl sulfolanylether mmol/l 0.1 Sodium saccharate g./-l 1.5 Sodium lauryl sulfate g./l 0.1 Current density arnperes/dm. 1-10 EXAMPLE 3 l-butenyl sulfolanylether mmol/l 0.5 Sodium saccharate g./l 1.0 Sodium tetrahydroxynaphthalene sulfonic acid g./l 1.0 Current density am-peres/dm. 2-15 EXAMPLE 4 Sodium hydroxyethylene-N- propargy-laminosulfolane mmol/l 0.5 Sodium saccharate g./l 1.5 Sodium oleinoylmethyl taurate g./l 0.1 Current density amperes/dm. 1-10 EXAMPLE 5 Propargyl sulfolanylether mmol/l 06 Naphthalene trisulfonic acid g./l 10 Sodium tetrahyd-roxy-naphthalene sulfonic acid g./l 1 Sodium sulfolanylmethyl taurate mmol/l 1 Current density amperes/dm. 2-15 EXAMPLE 6 Sodium sulfolanylpropargyl taurate mmol/l 0.5 Sodium saccharate g./l 1.5 Sodium octanoyl taurate g./l 0 1 Current density amperes/dm. 2-15 EXAMPLE 7 2-propenyl sulfolanylether mmol/l 10 Sodium saccharate g./l 1.5 Sodium tetrahydroxynaphthalene sulfonic acid g./l 1 Current density arnperes/dm. 1-10 EXAMPLE 8 Z-butenyl sulfolanylether mmol/l.. 1 0.1 Sodium tetrahydroxyn aphthalene sulfonic acid g./l l Cur-rent density amperes/dm. 1-10 EXAMPLE 9 2-butynyi sulfoianylether mmol/1 Current density ..amperes/dm...

EXAMPLE l iroxybutenyi suifoianylether --mmoi/L- rent density --amperes/dm.

EXAMPLE 11 -.-nydroxy Z-butynyl sulfolanylether mmoi/l-- Sodium saccharate --gJi-.. Sodium octanoyl cyclohexyi taurate --gJl..- Current density --amperes/dmL- EXAMPLE 12 Dihydroxydiethyieneamino sulfolane ..--mmol/i-- Curnent density --amperes/dmfi..-

EXAMPLE l3 Ethanolamino suli'olane ..mmol/l Sodium sacchnrate g./l.. Current density --amperes/dmL- EXAMPLE l4 Nhydroxyethylene-N-propargylamino sull'olane i-.. p-toluene suifonamide -.'-g./i..'. Current density -...amperes/dm.'....

EXAMPLE l5 N-butyl-N-propnrgyiamino suifolane L- Sodium iauryi sulfate g./i Current density --ampenes/dm)..-

EXAMPLE 16 2-propenyiamino su'i'olane --mmoi/L- Sodium tetarhydroxynaphthalene sullonic acid g /l Current density --amperes/dmL- EXAMPLE 11 N-hydoxyethyiene-N-2-propenylnmino ilfolane mmol/l..- ium iauryl suii'ate' --g./l-- rcnt density --amperes/dm'-..

EXAMPLE l8.

utyl-N-propargylamino sulfolane -.emmol/i..- rent density --amperes/dmh- EXAM'PLE l9 J-suiioinnol A i/i..- Sodium saccharine g./i-- Current density --ampenes/dm'" EXAMPLE 20 N'-propargylamino N ethyleneamino suitolane oi/i..- Sodium saccharate g./i

Current density --amperes/dmfi-..

EXAMPLE 21 Sodium sulfolanyi taurate (Sulfoianyi-aminoethyiene suifonic acid, sodium salt) --mmol/L- 5 Current density --amperes/dmfi-.. 1-10 EXAMPLE 22 Sodium sulfolanyimethyi taurate (Sulfoianyi-aminomethyl N-ethylene sulfonic acid, sodium salt) mmoi/L. 1 Sodium saccharate -..'..--g./l.. 1 Current density --amperes/dmfi..- l-lO EXAMPLE 23 Sodium auifoianyi propargyi taurate mmol/i 10 Current density --amperes/dmkl-l0 EXAMPLE 24 Acryi sulfolanylester chloride --mmoi/L- 1 Sodium saccharate --g./i 1 Current density --amperes/dmfi..- 2-15 EXAMPLE 25 Tetraamino-tetraethylene aminosulfoiane mmoi/L- 0.02 Naphthalene trisuifonic acid, sodium salt g./l 5.0 Sodium saccharate ..g./1 0.5 Sodium laurylsulfate --g./l-'.. 0.1

EXAMPLE 26 Propargyiamino triamino tetraethyiene aminosuifOlflIlO mmnl/l 0.01 Sodium saccharate g./i 0.5 Sodium laurylsulfate --gJi-.. 0.1

EXAMPLE 27 A Propargylamino diamino triethyiene aminosuifolane i/L- 0.02 Sodium saccharate ...g./i 0.5 Sodium lauryisuli'ate g./1 0.1

EXAMPLE 2a A Propargylamino amino-diethylene aminosult'oiane I rhmol/L- 0.02 Sodium saccharate g./i 0.5 Sodium iaurylsultate --g./l 0.1

The novel sultolene brightenersot the instant invention can also be used. in combination with any of the conventional brighteners of the second class (ievelers).

Synergistic eii'ects have been noted as illustrated in the following example.

EXAMPLE 29 Tetraamino-tetraethyiene aminosultoian'e mmol/l-.. 0.02 'Bis-hydro'xyethyl ether of butynedioi ..g./l.. 0.025 Sodium saccharate g./l 0.5 Sodium iauryisultate --gJi-.. 0.1

What is claimed is:

1. An aqueous acid bath solution for electroplating nickel containing at least one nickel salt as a source of nickel which plating solution includes as brightener a sufficient amount of a compound selected from the group consisting of compounds having the structural formula cals and X is halogen.

2. The nickel plating solution of claim 1 which includes a wetting agent having the formula Ih-N-Rr-BOs-lh wherein R is an alkanoyl radical having 8 to 10 carbon atoms; R, is selected from the group consisting of hydrogen, aliphatic, alicyclie and aromatic radicals; R, is an aliphatic bridge containing from i to carbon atoms and R is selected from the group consisting of hydrogen and alkali metal.

3. The nickel plating solution of claim 2 wherein the wetting agent is present in amounts of 0.5 to 5 g./l. of solution.

4. The nickel plating solution of claim 1 which ineludes a hydroxy derivative of an aromatic sulfur compound as a sequestering agent.

5. The nickel plating solution of claim 4 wherein the hydroxy derivative of an aromatic sulfur compound is sodium tetrahydroxynahphthalene sulfonic acid.

6. The nickel plating solution of claim 4 wherein the hydroxy derivative of an aromatic sulfur compound is present in amounts of 0.1 to 5 g./l. of solution.

7. The nickel plating solution of claim 1 wherein the brightener is present in amounts of 0.01 to mmol/l. of solution.

8. The nickel plating solution of claim 1 which includes as an additional brightener an aromatic sulfur compound.

9. The nickel plating solution of claim 8 wherein the additional brightener is sodium saecharate.

10. The nickel plating solution of claim 8 wherein the additional brightener is naphthalene trisulfonic acid.

11. An aqueous acid bath solution for electroplating nickel containing at least one nickel salt as a source of nickel which plating solution includes as first brightener a sufficient amount of a compound selected from the group consisting of compounds having the structural formula ing 1 to.6 carbon atoms,

: wherein R, R;, R, and R,

wherein R, R R and R are selected from the group consisting of hydrogen, alkanyl, alkenyl and alkynyl radicals, said alkanyl, alkenyl and alkynyl radicals havhydroxy derivatives of said alkanyl, alkenyl and alkynyl radicals, amino radicals and sulfonic acid radicals and X is halogen.

12. The nickel plating solution of claim 11 which includes a wetting agent having the formula 's-IIl-Bs-SWR:

wherein R is an alkanoyl radical having 8 to 10 carbon atoms; R is selected from the group consistin of hydrogen, aliphatic, alicyelic and aromatic radicals; R is an aliphatic bridge containing from i to 5 carbon atoms and R is selected from the group consisting of hydrogen and alkali metal.

13. The nickel plating solution of claim 12 wherein the wetting agent is present in amounts of 0.5 to 5 g/l. of solution.

14. The nickel plating solution of claim 11 which includes a hydroxy derivative of an aromatic sulfur compound as a sequestering agent.

15. The nickel plating solution of claim 14 wherein the hydroxy derivative of an aromatic sulfur compound is sodium tetrahydroxynaphthalene sulfonic acid.

16. The nickel plating solution of claim 14 wherein the hydroxy derivative of an aromatic sulfur compound is present in amounts of 0.1 to 5 g/l. of solution.

17. The nickel plating solution of claim 11 wherein said first brightener is present in amounts of 0.01 to 10 mmol/l. of solution.

18. The nickel plating solution of claim 11 which additionally includes as a second brightener an aromatic sulfur compound present in amounts of 0.1 to 30 g/l. of solution.

19. The nickel plating solution of claim 18 wherein said aromatic sulfur compound is sodium saecharate.

20. The process of producing nickel deposits of improved ductility and corrosion resistance characteristics on a metal base which comprises electrodepositin nickel from an aqueous acid bath containing nickel mainlyjn the form of a soluble inorganic salt, in the presence of a brightener selected from the group consisting of compounds having the structural formula t Ciir-ClI-OR, Clls-CliN Us Iii bill II: Rs 0 o o o and . moooon-cu-x 1 bill are selected from the group consisting of hydrogen, alkanyl, alkenyl and alkynyi radicals, hydroxy derivatives of said alkanyl, alkenyl and alkynyl radicals, amino radicals and sulfonic acid radicals and X is halogen, said brightener being present in an amount sutiicient to produce a bright nickel deposit.

21. The process of claim 20 wherein the brightener is present in amounts of 0.01 to 10 mmol/l. of solution.

22. The process of claim 20 wherein said bath includes an aromatic sulfur compound..

23. The process of claim 22 wherein said brightener is present in amounts of 0.05 to 5 mmol/l. of solution and said aromatic sulfur compound is present in amounts of 0.1 to 30 g/l. of solution.

24. The process of claim 20 wherein said bath includes a wetting agent having the formula R4N-RuSO3 7 wherein R is an alkanoyl radical having 8 to 10 carbon atoms; R is selected from the group consisting of hydrogen, aliphatic, alicyclic and aromatic radicals; R is an aliphatic bridge containing from 1 to 5 carbon atoms and R is selected from the group consisting of hydrogen and alkali metal, said wetting agent being present in amounts of 0.5 to 5 g/l. of solution.

25. The process of claim 20 wherein said bath includes a hydroxy derivative of an aromatic sulfur compound as a sequestering agent.

26. The process of claim 25 wherein the hydroxy derivative of an aromatic sulfur compound is sodium tetrahydroxynaphthalene sulfonic acid.

References Cited UNITED STATES PATENTS Morris et a1. 260-3321 Morris et a1. 260-3321 Moy 20449 Brown 20449 Passal et a1. 20449 Loev 260-332.1 XR Ericson 204-49 Ericson 20449 Fritz et a1. 260--332,1

1 HOWARD S. WILLIAMS, Primary Examiner.

G. KAPLAN, Assistant Examiner. 

1. AN AQUEOUS ACID BATH SOLUTION FOR ELECTROPLATING NICKEL CONTAINING AT LEAST ONE NICKEL SALT AT A SOURCE OF NICKEL WHICH PLATING SOLUTION INCLUDES AS BRIGHTENER A SUFFICIENT AMOUNT OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS HAVING THE STRUCTURAL FORMULA 